1. Field of the Invention
The present invention relates to apparatus and method for transferring a very small amount of liquid (micro-liquid) using a pin tool.
2. Description of the Related Art
In the field of biochemistry, there are carried out various kinds of analyses on a very small amount of sample held in the well of a micro plate. As a method for transferring a small amount of sample, there is generally known a method that uses multiple wells formed in a micro plate and a pin tool that is an aggregate of multiple pins respectively situated at positions corresponding to their associated wells. A specific groove working is executed in the leading ends of the respective pins. When such leading end portions of the pins are immersed in a sample that is stored in a container, a given amount of sample is attached to the respective pins due to the action of the surface tension. The sample attached to the pin leading end portion is contacted with the inner walls of the wells to transfer the sample thereto or to mix the sample with a liquid previously held in the wells, thereby transferring the sample. When the same pin tool is used to transfer another kind of sample, the pins must be immersed into a specific washing solution from the leading ends of the pins, the pins must be washed using ultrasonic waves and must be then rinsed using pure water, and the pins must be vacuum dried, thereby removing the attached substances from the pins completely (see the patent references 1 to 3).    Patent Reference 1: JP-A-2003-329680    Patent Reference 2: JP-A-2004-518115    Patent Reference 3: JP-A-2004-532983
Here, for the washing of the pins, there is necessary at least the time that includes about 30 seconds for the ultrasonic washing of the pins and about 10 seconds respectively for the rinsing and drying of the pins. This time provides a so-called operation waiting time while the sample transfer operation is interrupted because the pin tool is restricted by the washing operation. Therefore, when carrying out continuously the operations to transfer samples of different kinds, the operation waiting time is accumulated each time the sample to be handled is changed, resulting in the lowered productivity.